Attachment of sprinklers to pipe elements of a fire suppression system is time consuming and must be executed with care to ensure that: 1) a fluid tight joint is effected, 2) the relatively delicate sprinkler is in operating condition after it is installed, and 3) that certain regulatory requirements, such as rotational orientation, are met. Traditional sprinklers have a body with a nipple that has male threads which engage the female threads of an adapter fitting connected to the pipe element, usually also a threaded or welded attachment. These sprinklers generally also have a frame, or frame arms, extending from the body in a direction opposite the nipple. The frame or frame arms support a deflector that acts to appropriately distribute and disburse the fluid which is discharged by the sprinkler through a bore which extends through the body. These sprinklers are commonly oriented in any of an upright, pendent, or sidewall configurations. These configurations are distinguished by the direction of the axis of the bore of the sprinkler, and thus of the direction of the water discharged from the orifice at the end of the bore before it impinges upon the deflector, examples of those directions being vertically upwards, vertically downwards, and horizontally for the upright, pendent, and sidewall sprinklers, respectively. Further, the installation of certain types of sprinklers may require, for regulatory or functional reasons, that they be installed in a certain rotational orientation about their axis and relative to the space to be protected by the sprinkler. This rotational orientation requirement is different from the pendent, upright, or sidewall orientation of the sprinkler body (and thus of the axis), but refers to the rotational orientation of the sprinkler body about its axis, which affects the location of the frame, frame arms or the deflector. For instance, sidewall-type sprinklers typically have a deflector which is asymmetrical about the sprinkler's axis, and that acts to preferentially deflect the discharged fluid downwards and out of the sprinkler, while limiting the fluid from that is deflected upwards. The rotational alignment of such a deflector about the horizontal axis of the sprinkler body is critical to ensure adequate protection of the space where the sprinkler is installed. Additionally, certain regulations, including those promulgated by the National Fire Protection Agency (NFPA) require certain orientations for various types of sprinklers to ensure the desired and necessary performance.
Attachment of a traditional sprinkler to their adapter fittings requires that the technician ensure that each threaded joint is sealed and that the sprinkler is not damaged when handled or when torque is applied to seat the sprinkler during installation. The threaded joints for attaching sprinklers are commonly of the tapered thread type, which have a built-in interference which causes the threads to create a seal when they are sufficiently tightened. However, this seal can be compromised in many ways, including by damage to the threads, incomplete tightening, corrosion, or other forms of contamination of the mating surfaces. This attachment is further complicated by the rotational orientation requirement, where an installer not only has to ensure adequate tightness, but also the appropriate rotational orientation, which may mean tightening the sprinkler up to one full rotation more or less than might otherwise be desired. As these tapered threads require increasing torque with rotation, it may not be possible to achieve the appropriate orientation with additional tightening, causing the installer to ‘back off’ the sprinkler to a looser condition with the correct orientation, or risk damaging the sprinkler by overtightening it. In an attempt to mitigate any of the above conditions and promote more consistent attachment of sprinklers, installers will often use a thread sealant, such as pipe joint compound, or thread sealing tapes, to help promote a seal under less than ideal conditions; however, thread sealant or tape may exacerbate leakage issues where sprinklers are tightened and loosened repeatedly while trying to achieve the appropriate orientation. Use of sealants and tapes add time and expense to the installation process. Further, excess tape or compound may prevent the sprinkler from being threaded into the adapter fitting to the appropriate depth necessary for safe operation.
As the required leak-tight nature of sprinklers relies on interference inherent in tapered thread connections, combined with sealants and tapes when used, tightening often requires significant torque, especially as for sprinklers having large orifices, and, consequently larger bodies, such as those that are connected with ¾″ or 1″ National Pipe Thread or British Standard Pipe size threads. The need to apply significant torque in the vicinity of the sprinkler's delicate components, such as the deflector and, in automatic-type sprinklers, the fusible element that triggers the sprinkler (commonly a solder link or glass bulb), heightens the risk of damage to these components during assembly. Attempts to mitigate this risk include specialized wrenches and regulations that require covers, commonly called bulb protectors, be installed over the most delicate sprinkler components in order to shield them during installation. Example covers are disclosed in U.S. Pat. No. 7,273,189, hereby incorporated by reference.
There is clearly an opportunity to improve the installation of sprinklers by reducing the time required for installation, reducing the number of parts to be handled, reducing the likelihood of damage to the sprinkler, promoting more consistent sealing, and more easily achieving the required rotational orientation.